Bump Sidekiq 5.1.3 to 5.2.1

See merge request gitlab-org/gitlab-ce!21624

Bump gitlab-shell to 8.3.1

See merge request gitlab-org/gitlab-ce!21648

docs: Correct YAML indentation

See merge request gitlab-org/gitlab-ce!21631

8.3.0 was tagged with the commit before the CHANGELOG.md and
version.rb bump, so this just fixes a harmless warning.

Add `duration` attributes to Jobs API docs

See merge request gitlab-org/gitlab-ce!21626

Add changelog to !21371

See merge request gitlab-org/gitlab-ce!21615

Add /lock and /unlock quick actions

Closes #39173

See merge request gitlab-org/gitlab-ce!15197

Replace one word in todos.md

See merge request gitlab-org/gitlab-ce!19757

Update doc: url reference to grafana

See merge request gitlab-org/gitlab-ce!21637

Clean up chart index page

See merge request gitlab-org/gitlab-ce!21623

Make topic adhere to style guide

See merge request gitlab-org/gitlab-ce!21582

Specify tar is required for backup and restore tasks

Closes omnibus-gitlab#2334

See merge request gitlab-org/gitlab-ce!21633

Merge branch 'docs/51295-update-documentation-for-interactive-web-terminals-to-remove-beta-indicator' into 'master'

Remove beta from web terminal documentation

Closes #51295

See merge request gitlab-org/gitlab-ce!21641

Document permissions for different entities

Closes #50036

See merge request gitlab-org/gitlab-ce!21109

[QA] Fix arguments passed to RSpec::Core::Runner

See merge request gitlab-org/gitlab-ce!21578

closes gitlab-org/gitlab-ce#51295

Enable frozen string for app/helpers/**/*.rb

See merge request gitlab-org/gitlab-ce!21320

Fix LDAP QA specs failing due to button change

See merge request gitlab-org/gitlab-ce!21622

Update templates and licenses for 11.3

See merge request gitlab-org/gitlab-ce!21611

Resolve "On master, inline diff view contains extra `+` and `-` signs"

Closes #51281

See merge request gitlab-org/gitlab-ce!21634

Disable query limit counter in sidekiq

See merge request gitlab-org/gitlab-ce!21470

API: Use find_branch! in all places

Closes #51250

See merge request gitlab-org/gitlab-ce!21614

Explicitly enable usage ping for instance statistics spec

Closes #51294

See merge request gitlab-org/gitlab-ce!21629

Fix QA builds failing due to change in new project page behavior

Closes gitlab-qa#322

See merge request gitlab-org/gitlab-ce!21621

This is similar to https://gitlab.com/gitlab-org/gitlab-ee/issues/7511, but
the root cause is https://gitlab.com/gitlab-org/gitlab-ce/issues/51268.

Add system note when due date is changed

Closes #38208

See merge request gitlab-org/gitlab-ce!21628

This is similar to https://gitlab.com/gitlab-org/gitlab-ee/issues/7511, but
the root cause is https://gitlab.com/gitlab-org/gitlab-ce/issues/51268.

Update invite_group_spec to be consistent with EE

See merge request gitlab-org/gitlab-ce!21608

The most significant change in this version is that the default
concurrency has been lowered from 25 to 10 (https://github.com/mperham/sidekiq/issues/3892).
This doesn't affect omnibus-gitlab because the concurrency is controlled via a
setting that defaults to 25 anyway and is passed in via the `-c` command-line
parameter.

However, source installations (including the GDK) will have to either specify
the concurrency in `sidekiq.yml` or use the `-c` option.

Full list of changes: https://github.com/mperham/sidekiq/blob/master/Changes.md

Follow up to !13644.

The LDAP tab is no longer a button, but is now a link. Update the QA page
to check for a link.